Snowmobile having improved clearance for deep snow

ABSTRACT

A snowmobile comprises a chassis with a front portion and a tunnel, and a power train unit supported by the chassis. The snowmobile further includes a plurality of ground-engaging members cooperating with the power train unit to operate the snowmobile. The plurality of ground-engaging members includes a pair of front skis and an endless track assembly. A snowmobile is also depicted which has a raised front chassis relative to the drives haft, which raises the clearance of the front chassis for deep snow.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/563,964 filed Aug. 1, 2012, which claims priority to U.S. provisionalpatent application Ser. No. 61/513,949 filed Aug. 1, 2011 and U.S.provisional patent application Ser. No. 61/582,426 filed Jan. 2, 2012,the subject matter of which is incorporated herein by reference.

BACKGROUND OF THE DISCLOSURE

The present disclosure relates to snowmobiles and, more particularly, tosnowmobiles for use in deep snow applications.

Generally, snowmobiles are available for various applications such asdeep snow, high performance, luxury touring, and trail riding, forexample. Regardless of the application, certain structural componentsare common to many snowmobiles. For example, snowmobiles typicallyinclude a frame, a track assembly, a power train, skis, and at least onesuspension system, as are illustrated in U.S. Patent ApplicationPublication No. 2011/0139528, filed on Feb. 14, 2011, U.S. PatentApplication Publication No. 2011/0192667, filed on Feb. 4, 2011, U.S.Pat. No. 7,353,898, issued on Apr. 8, 2008, and U.S. ProvisionalApplication Ser. No. 61/513,949, filed on Aug. 1, 2011, the completedisclosures of which are expressly incorporated by reference herein.

One common area for snowmobiles generally relates to the overallarchitecture, where a frame includes a tunnel and a front chassisportion which retains the power train, and a front suspension thatmounts skis to the frame. A drive shaft is typically mounted to thefront chassis portion and includes drive sprockets for powering thebelt. A chain case is also typically provided to transfer power from anengine or CVT to the drive shaft. Reference is made to U.S. Pat. No.7,694,768 which shows a typical snowmobile drivetrain with a drive shaftand an upper jack shaft that drives the drive sprockets through thechain case, the subject matter of which is incorporated herein byreference.

In the case of mountain or deep snow snowmobiles, one commoncharacteristic is to provide an elongated endless belt to provide alonger footprint for the belt, and a lower pressure for the snowmobilefor flotation in deep snow. An elongated tunnel is also provided tocover the extended belt. A front body typically surrounds at least thefront frame portion to enclose the engine and other mechanicalcomponents. Reference is made to U.S. Pat. No. 7,870,920 and to U.S.patent application Ser. No. 13/021,586 both of which show deep snowsnowmobiles, the subject matter of each being incorporated herein byreference. A present version of a snowmobile frame for deep snow isshown in FIG. 1.

SUMMARY OF THE DISCLOSURE

An illustrative embodiment of the present disclosure includes asnowmobile comprising a chassis having a front portion and a tunnel, thefront portion having a front frame portion having an engine mountportion, the engine mount portion having a lower edge and a drive shaftmount portion, the drive shaft mount portion extending lower than thefront lower edge. A propulsion unit comprises a drive shaft, the driveshaft being rotatably coupled to the chassis drive shaft mount portionwith an outer diameter of the drive shaft being spaced from the frontlower edge of the chassis. A front suspension comprises right and leftupper control arms, right and left lower control arms, a right spindlecoupled to the right upper control arm and right lower control arm, anda left spindle coupled to the left upper control arm and left lowercontrol arm. Skis are coupled to a lower end of the right and leftspindles at ski coupling points; and a rear suspension coupled to thetunnel comprising a front control arm and at least one slide rail, wherethe front control arm is coupled to the tunnel at a control arm couplingpoint. A linear distance between a connection point of the right andleft lower control arms of the front suspension to respective right andleft spindles and the ski coupling points for the right and leftspindles is approximately in the range of 6-7″; a vertical distance froma bottom of the ski to the lower edge of the front frame portion isapproximately in the range of 8-10″; and a vertical distance from thelower edge of the front frame portion to the control arm coupling pointis approximately in the range of 3-4.25″.

An illustrative embodiment of the present disclosure includes asnowmobile comprising a chassis having a front portion and a tunnel, thefront portion having a front frame portion having an engine mountportion, the engine mount portion having a lower edge and a drive shaftmount portion, the drive shaft mount portion extending lower than thefront lower edge. A propulsion unit comprises a drive shaft, the driveshaft being rotatably coupled to the chassis drive shaft mount portionwith an outer diameter of the drive shaft being spaced from the frontlower edge of the chassis. A front suspension comprises right and leftupper control arms, right and left lower control arms, a right spindlecoupled to the right upper control arm and right lower control arm, anda left spindle coupled to the left upper control arm and left lowercontrol arm. Skis are coupled to a lower end of the right and leftspindles at ski coupling points; and a rear suspension coupled to thetunnel comprising a front control arm and at least one slide rail, wherethe front control arm is coupled to the tunnel at a control arm couplingpoint. A linear distance between a connection point of the right andleft lower control arms of the front suspension to respective right andleft spindles, and a connection point between the skis and the lowerends of the right and left spindles is approximately greater than 6″; avertical distance from a bottom of the ski to the lower edge of thefront frame portion is approximately greater than 8″; and a verticaldistance from the lower edge of the front frame portion to the controlarm coupling point is approximately less than 4.25″.

Additional features and advantages of the present invention will becomeapparent to those skilled in the art upon consideration of the followingdetailed description of the illustrative embodiment exemplifying thebest mode of carrying out the invention as presently perceived.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the intended advantages of thisinvention will become more readily appreciated as the same becomesbetter understood by reference to the following detailed descriptionwhen taken in conjunction with the accompanying drawings.

FIG. 1A is a side perspective view of a clutch side of an illustrativesnowmobile of the present disclosure;

FIG. 1B is a side perspective view of a belt drive side of thesnowmobile of FIG. 1A;

FIG. 2 is a front perspective of the snowmobile of FIG. 1;

FIG. 3 is a rear perspective view of a front frame portion of theillustrative snowmobile;

FIG. 4 is a front perspective view of the front frame portion and frontsuspension assembly of the illustrative snowmobile;

FIG. 5 is a front perspective view of a portion of a power train unit ofthe snowmobile of the present disclosure;

FIG. 6 is an exploded view of the portion of the power train unit ofFIG. 5;

FIG. 7 is an exploded view of an upper sprocket of the illustrativepower train unit;

FIG. 8 is an exploded view of a lower sprocket of the illustrative powertrain unit;

FIG. 9 is a cross-sectional view of the upper sprocket of FIG. 7, takenalong line 9-9 of FIG. 7;

FIG. 10 is a cross-sectional view of the lower sprocket of FIG. 8, takenalong line 10-10 of FIG. 8;

FIG. 11 is a side perspective view of a tool for assembling a belt driveshaft of the present disclosure;

FIG. 12 is front perspective view of a drive shaft of the illustrativepower train unit;

FIG. 13 is an end view of the drive shaft of FIG. 12 with an end capremoved;

FIG. 14A is an exploded view of the illustrative drive shaft of FIG. 12;

FIG. 14B is a further exploded view of the illustrative drive shaft;

FIG. 15 is a cross-sectional view of an adhesive cavity formed by theillustrative drive shaft;

FIG. 16 is a side plan view of an endless track of the illustrativesnowmobile supported on the drive shaft;

FIG. 17 is a front view of the front frame portion of the snowmobile ofthe present disclosure;

FIG. 18 is a perspective view of the front suspension and a ski of thesnowmobile;

FIG. 19 is a further perspective view of the front suspension of thesnowmobile;

FIG. 20A is an exploded view of the lower control arm of the frontsuspension of FIG. 19;

FIG. 20B is an exploded view of a shock absorber of the front suspensioncoupled to the lower control arm;

FIG. 21A is a cross-sectional view of a bracket of the lower control armof FIG. 20;

FIG. 21B is a cross-sectional view of an adhesive cavity formed by thelower control arm of and the bracket of FIG. 21A;

FIG. 22 is bottom perspective view of the front frame portion of thesnowmobile;

FIG. 23 is a front perspective view of an overstructure of theillustrative front frame portion of the present disclosure;

FIG. 24 is an exploded view of the overstructure of FIG. 23;

FIG. 25 is an exploded view of a portion of the overstructure of thepresent disclosure, including frame tubes and couplers;

FIG. 26 is a cross-sectional view of an adhesive cavity formed by theframe tubes and couplers of FIG. 25;

FIG. 27 is a rear perspective view of a steering assembly of theillustrative snowmobile;

FIG. 28 is a side perspective view of the front frame portion of thesnowmobile and including a brace tube;

FIG. 29 is a rear perspective view of the front frame portion and thebrace tube of the illustrative snowmobile of the present disclosure;

FIG. 30 is an exploded view of a steering rod of the illustrativesteering assembly of FIG. 27;

FIG. 31 is a cross-sectional view of an adhesive cavity formed by theillustrative steering rod of FIG. 30;

FIG. 32A is a cross-sectional view of a drag arm of the illustrativesteering assembly of FIG. 27;

FIG. 32B is a cross-sectional view of an adhesive cavity formed by theillustrative drag arm of FIG. 27;

FIG. 33A is a rear perspective view of the illustrative steeringassembly showing an auxiliary power button;

FIG. 33B is a detailed side perspective view of the auxiliary powerbutton of FIG. 33A;

FIG. 33C is a rear perspective view of an alternative embodiment of thesteering assembly of FIG. 33A;

FIG. 34A is a bottom perspective view of a rear suspension and a tunnelof the illustrative snowmobile of the present disclosure;

FIG. 34B is an exploded perspective view of a shock absorber of the rearsuspension;

FIG. 35 is a perspective view of the tunnel of FIG. 34;

FIG. 36 is a side perspective view of the tunnel of FIG. 35;

FIG. 37 is a cross-sectional view of the tunnel of the presentdisclosure including recessed channels;

FIG. 38 is a detailed view of the recessed channels of the tunnel ofFIG. 37;

FIG. 39A is an exploded view of a seat assembly of the illustrativesnowmobile of the present disclosure;

FIG. 39B is a further exploded view of the seat assembly of FIG. 39A;

FIG. 40 is a top plan view of the seat assembly with the seat coverremoved;

FIG. 41 is a side cross-sectional view of the seat assembly along alongitudinal axis of the seat assembly;

FIG. 42 is a rear cross-sectional view of the seat assembly;

FIG. 43 is a side view of the running board assembly and a toe gripassembly of the illustrative snowmobile;

FIG. 44 is a side perspective view of a portion of the running boardassembly of FIG. 43;

FIG. 45A is an exploded view of a bracket and an elongate frame memberof the running board assembly of FIG. 43;

FIG. 45B is an exploded view of an elbow and the elongate member of therunning board assembly of FIG. 43;

FIG. 46A is a cross-sectional view of an adhesive cavity formed by thebracket of FIG. 45A;

FIG. 46B is s cross-sectional view of an adhesive cavity formed by theelbow of FIG. 45B;

FIG. 47A is a side perspective view of a front torque arm of the rearsuspension;

FIG. 47B is an exploded view of a front torque arm of the rearsuspension of FIG. 34;

FIG. 48 is a cross-sectional view of an adhesive cavity formed by thefront torque arm of FIG. 47A;

FIG. 49 is a bottom perspective view of a rail assembly and the driveshaft of the snowmobile of the present disclosure;

FIG. 50A is a top perspective view of a mount for a regulator of theillustrative snowmobile;

FIG. 50B is a bottom perspective view of the mount of FIG. 50A;

FIG. 51A is a front perspective view of a mount for a solenoid and EVcoils of the illustrative snowmobile;

FIG. 51B is a bottom perspective view of the mount of FIG. 51A;

FIG. 51C is cross-sectional view of the mount of FIG. 51A, taken alongline 51C-51C of FIG. 51A;

FIG. 52 is a portion of an endless track of the snowmobile;

FIG. 53 shows a side view of a current version snowmobile;

FIG. 54 shows a front left perspective view of the main portions of adeep snow snowmobile;

FIG. 55 shows a left side view of the snowmobile of FIG. 54;

FIG. 56 shows an underside perspective view of the snowmobile frontframe;

FIG. 57 shows a right hand side enlarged view of the snowmobile of FIG.54;

FIG. 58 shows an enlarged view of the front left ski and its attachmentto the suspension system;

FIG. 59 shows an enlarged portion of the left front end of thesnowmobile of FIG. 55; and

FIG. 60 shows a cross sectional view through lines 60-60 of FIG. 59;

Corresponding reference characters indicate corresponding partsthroughout the several views. Although the drawings representembodiments of various features and components according to the presentdisclosure, the drawings are not necessarily to scale and certainfeatures may be exaggerated in order to better illustrate and explainthe present disclosure. The exemplifications set out herein illustrateembodiments of the invention, and such exemplifications are not to beconstrued as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION OF THE DRAWINGS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings, which are described below. The embodiments disclosed beloware not intended to be exhaustive or limit the invention to the preciseform disclosed in the following detailed description. Rather, theembodiments are chosen and described so that others skilled in the artmay utilize their teachings. For example, while the followingdescription refers primarily to a snowmobile, it should be understoodthat the principles of the invention apply equally to other snowvehicles. While the present invention primarily involves a snowmobile,it should be understood, however, that the invention may haveapplication to other types of vehicles, such as motorcycles, ATVs,utility vehicles, scooters, and mopeds.

Referring to FIGS. 1A, 1B, and 2, an illustrative embodiment of asnowmobile 10 includes a chassis or frame 12 including a front frameportion 12 a and a rear frame portion 12 b. Front frame portion 12 a issupported by front ground-engaging members, illustratively skis 14, andrear frame portion 12 b is supported by a rear ground-engaging member,illustratively an endless track 16. Front skis 14 are operably coupledto a front suspension assembly 18, and endless track 16 cooperates witha rear suspension assembly 20. Snowmobile 10 also includes a seatassembly 22, a front outer body (not shown), and a steering assembly 26.

Referring to FIGS. 5-16, a power train unit 30 (FIG. 5) is covered by anouter body panel (not shown) and provides power to endless track 16 tomove snowmobile 10. As shown in FIG. 5, power train unit 30 is supportedby front frame portion 12 a and includes an engine 28 (FIG. 1A), aclutch assembly 32 of the continuously variable transmission (“CVT”)type, a belt drive assembly 34, a drive shaft 36, and a jackshaft 38. Abrake assembly 84 may be positioned adjacent jackshaft 38.

With reference now to FIGS. 1A-4, and 28, frame 12 includes a bulkhead186 coupled to tunnel 39. Bulkhead 186 comprises a front casting havingmirror image castings 188 and 190 (FIG. 28). Bulkhead 186 extends alongthe right (denoted as 186 a) and left side (denoted as 186 b) of frontframe portion 12 a. Bulkhead 186 further comprises an engine cradle 40coupled to right and left castings 188, 190 to support power train unit30. Engine cradle 40 includes a plurality of bushings to support engine28 therein. Bulkhead member 186 a illustratively supports belt driveassembly 34 and bulkhead member 186 b illustratively supports clutchassembly 32 (FIGS. 1A and 1B).

As best shown in FIGS. 1B and 3, engine 28 is coupled to an exhaustassembly 86 which receives exhaust gases from engine 28. Exhaustassembly 86 is in fluid communication with a resonator 87 to expel theexhaust gases from a fluid port (not shown) in resonator 87. Resonator87 is coupled to a resonator mount 88 supported by bulkhead 186. Inparticular, resonator mount 88 is adjacent bulkhead member 186 a andspans engine cradle 40. Resonator mount 88 has spring connections forcoupling to resonator 87. The construction and materials of resonatormount 88 may contribute to an overall weight reduction of snowmobile 10relative to a conventional mounting apparatus (e.g., a saddle mount).

Referring to FIGS. 5-16, engine 28 is operably coupled to clutchassembly 32 through the crankshaft (not shown) of engine 28. Moreparticularly, clutch assembly 32 couples engine 28 to drive shaft 36.Clutch assembly also includes a housing 33. While illustrative clutchassembly 32 includes a CVT, clutch assembly 32 may embody other types ofclutches. As is known, a CVT includes a drive clutch (not shown), whichis operably coupled to engine 28, and a driven clutch 44. Driven clutch44 is illustratively supported by bulkhead member 186 b (FIG. 6) and iscoupled to the drive clutch through a drive belt (not shown).

Driven clutch 44 is operably coupled to drive shaft 36 through beltdrive assembly 34 and jackshaft 38, as further detailed hereinafter.Belt drive assembly 34 includes a housing 46, an upper sprocket 48, alower sprocket 50, and a belt 52. As illustrated in FIG. 1B, housing 46is supported by bulkhead 186, illustratively bulkhead member 186 a, andis coupled thereto with conventional fasteners. Upper sprocket 48 isoperably coupled to lower sprocket 50 with belt 52. Illustrative uppersprocket 48 has a smaller diameter than that of lower sprocket 50,however, the size of upper and lower sprockets 48, 50 may change toaccommodate different gearing ratios.

Referring to FIGS. 5-11, upper sprocket 48 includes a hub 56 and acenter portion 58. Hub 56 includes outer teeth 54 that rotatably couplewith belt 52, and a guide flange 49 to retain belt 52 on upper sprocket48. Guide flange 49 extends from the outer side of upper sprocket 48 andis adjacent outer teeth 54. Hub 56 is integrally formed around centerportion 58, and more particularly, is cast around center portion 58.Center portion 58 includes an inner spline 60 which operably couplesupper sprocket 48 to jackshaft 38. Center portion 58 also includes aprofiled outer surface. Illustratively, the profiled outer surface ofcenter portion 58 includes extension members 62, which may be teeth,projections, guides, cogs, ribs, or other members extending from centerportion 58. The profiled outer surface of center portion 58 may also beotherwise formed, such as with indentations, recesses, or grooves, forexample. Illustratively, portions of hub 56 are cast between extensionmembers 62 of center portion 58.

Lower sprocket 50 also includes a hub 66 and a center portion 68. Hub 66includes outer teeth 64 and a guide flange 70. Outer teeth 64 rotatablycouple belt 52 to lower sprocket 50. Guide flange 70 extends outwardlyfrom the inner surface of lower sprocket 50 and is adjacent to outerteeth 64. Guide flange 70 of lower sprocket 50 cooperates with guideflange 49 of upper sprocket 48 to closely align the center of gravity ofbelt 52 with the center of gravity of upper and lower sprockets 48, 50.

Similar to upper sprocket 48, hub 66 of lower sprocket 50 is integrallyformed around center portion 68, more particularly, is cast aroundcenter portion 68. Center portion 68 includes an inner spline 72 whichoperably couples lower sprocket 50 to drive shaft 36. Center portion 68also includes a profiled outer surface. Illustratively, the profiledouter surface of center portion 68 includes extension members 74, whichmay be teeth, projections, guides, cogs, ribs, or other membersextending from center portion 68.

Referring to FIGS. 7-10, center portions 58, 68 may be comprised ofmetal, for example a powdered metal, and formed through a conventionalsintering process. Center portions 58, 68 are formed prior to formingupper and lower sprockets 48, 50. For example, center portions 58, 68are formed and positioned within a cast or mold prior to casting upperand lower sprockets 48, 50 so as to be integrally formed in the centerportion of upper and lower sprockets 48, 50.

After casting, upper and lower sprockets 48, 50 may be coated or plated.In one embodiment of the present disclosure, illustrative upper andlower sprockets 48, 50 are electroplated with a metal. The metal may benickel or chrome, for example. During the plating process, centerportions 58, 68 may be covered, masked, or otherwise sealed to preventdamaging or undesirably altering center portions 58, 68. Upper and lowersprockets 48, 50 may also undergo further treatment processes, such asetching.

Referring to FIG. 11, belt 52 is a toothed belt drive and has an innertoothed surface 76 and an outer surface 78 forming a circle incross-section. Belt 52 may be comprised of a polymeric material, forexample rubber. Outer surface 78 is generally flat or smooth. Innersurface 76 includes teeth 80 which are sized to receive outer teeth 54,64 of upper and lower sprockets 48, 50, respectively.

Belt drive assembly 34 is a synchronous, perfect pitch assembly. Moreparticularly, belt 52 is in perfect tension when assembled with upperand lower sprockets 48, 50. To ensure that belt drive assembly 34 is inperfect tension, upper sprocket 48 and lower sprocket 50 are assembledwith belt 52 before coupling with jackshaft 38 and drive shaft 36,respectively. More particularly, upper sprocket 48 threadedly coupleswith teeth 82 of jackshaft 38 and lower sprocket 50 threadedly coupleswith teeth 112 of drive shaft, as further detailed hereinafter.

As shown in FIG. 11, a tool 500, or other device, may be used toassemble belt drive assembly 34 in perfect tension. Tool 500 includespins 502 a, 502 b which may be used to simultaneously mount upper andlower sprockets 48, 50 and belt 52 to jackshaft 38 and drive shaft 36.Illustratively, pins 502 include a first end portion 504 and a secondend portion 506. First end portions 504 of pins 502 are tapered orotherwise angled relative to second end portion 506. The diameter ofsecond end portion 506 is slightly smaller than the inner diameter ofinner splines 60, 72 of upper and lower sprockets 48, 50. Likewise, thediameter of second end portion 506 is slightly smaller than the outerdiameter of teeth 82 of jackshaft 38 and teeth 112 of drive shaft 36.

During assembly of belt drive assembly 34, pins 502 are coupled to theoutermost surface of teeth 82 and 112 and extend outwardly therefrom.Belt 52 is assembled around upper and lower sprockets 48, 50. Upper andlower sprockets 48, 50 simultaneously slide onto first end portion 504and along second end portion 506 of pins 502 a, 502 b, respectively. Assuch, upper and lower sprockets 48, 50, along with belt 52, slide ontoteeth 82, 112 of jackshaft 38 and drive shaft 36, respectively. Afterassembly of belt drive 34, pins 502 may be removed and fasteners areused to couple belt drive assembly with jackshaft 38 and drive shaft 36.Belt 52 remains in perfect tension with upper and lower sprockets 48, 50during assembly of belt drive assembly 34.

Belt drive assembly 34 may replace a traditional chain drive assemblybecause belt 52, rather than a chain, is used with upper and lowersprockets 48, 50. Without a chain, belt drive assembly 34 does notrequire an oil pan or a sealed chain case. Furthermore, because beltdrive assembly 34 does not include a chain and is in perfect tension, atensioner also is not required. As such, the weight of illustrative beltdrive assembly 34 may be less than that of a traditional chain driveassembly. By decreasing the weight of belt drive assembly 34, the weightand inertia of power train assembly 30 also may be reduced, therebyreducing the weight of snowmobile 10. Additionally, belt drive assembly34 requires less maintenance than a chain drive assembly because beltdrive assembly 34 does not experience traditional maintenance problems,such as oil leaks.

As detailed above and shown in FIGS. 5 and 6, upper sprocket 48 of beltdrive assembly 34 is coupled to driven clutch 44 of clutch assembly 32via jackshaft 38. Jackshaft 38 includes a first portion 38 a and asecond portion 38 b. More particularly, jackshaft 38 may be gun drilledor formed through similar methods such that second portion 38 b issubstantially hollow and may receive first portion 38 a therein.Illustrative first portion 38 a is coupled to driven clutch 44 withconventional fasteners (e.g., bolts, rivets). Illustrative secondportion 38 b includes teeth 82 (FIG. 11), that couple with inner spline60 of upper sprocket 48. It may be appreciated that the substantiallyhollow, two-piece construction of gun drilled jackshaft 38 also reducesthe overall weight of snowmobile 10.

In one embodiment of the present disclosure, a speed sensor 492 (FIG. 6)may be positioned adjacent upper sprocket 48 and brake assembly 84.Speed sensor 492 is in electronic communication with an engine controlunit (“ECU”) (not shown) to determine the speed (e.g., in miles per hourduring) operation of snowmobile 10. Alternative embodiments of speedsensor 492 may determine the speed by recording a number of pulses perunit time. The ECU is programmed to receive a signal from speed sensor492 indicative of a measurement per unit time and to output a speed inmiles/hour on a display (not shown) that is visible to the rider. Speedsensor 492 may be calibrated in order to accommodate various gearingratios of belt drive assembly 34.

As previously detailed, lower sprocket 50 is coupled to drive shaft 36.As illustrated in FIGS. 5, 6, 11, and 35, drive shaft 36 is coupled toframe 12 below jackshaft 38. Referring to FIGS. 12-15, a drive shaftassembly includes drive shaft 36, which has an interior portion 90 andan external surface 92 extending between first and second ends 94, 96.The drive shaft assembly also includes a first end cap 108 and a secondend cap 118. Illustratively, external surface 92 of drive shaft 36defines a hexagon in cross-section formed by six apexes 93 and six sides95. Certain illustrative embodiments of drive shaft 36 may define othershapes in cross-section (e.g., a circle). The hexagonal shape of driveshaft 36 may facilitate torque transfer when additional driving force isexerted on drive shaft 36. Drive shaft 36 is comprised of an extrudablematerial, for example aluminum, and formed through conventionalextrusion processes.

Illustrative interior portion 90 of drive shaft 36 includes internalribs 98 extending substantially along the length of drive shaft 36. Asshown in FIGS. 16-20, internal ribs 98 are proximate first and secondends 94, 96 but may not extend into first and second ends 94, 96. Theillustrative embodiment of drive shaft 36 includes three internal ribs98, however, the number of internal ribs 98 may vary to accommodatespecific materials, shapes of drive shaft 36, applications of snowmobile10, and torque loads. Internal ribs 98 define three substantially hollowchannels within interior portion 90 of drive shaft 36. Moreparticularly, internal ribs 98 intersect apexes 93 in an alternatingpattern. As such, illustrative internal ribs are spaced apart from eachother by at least one apex 93 and at least two sides 95. Additionally,internal ribs 98 intersect each other along a longitudinal axis l ofdrive shaft 36, as shown in FIGS. 14A and 14B. In one embodiment, driveshaft 36 defines a circle in cross-section and interior portion 90 doesnot include internal ribs 98.

As further shown in FIGS. 12-16, external surface 92 may includeexternal ribs 100. Illustratively, external ribs 100 extend outwardlyfrom external surface 92 and are positioned at alternating apexes 93 ofdrive shaft 36. As with internal ribs 98, external ribs 100 are spacedapart from each other by at least an apex 93 and at least two sides 95.More particularly, external ribs 100 are positioned at one apex 93 thatis not intersected by internal ribs 98. As such, external ribs 100 arepositioned between internal ribs 98. By alternating the arrangement ofexternal ribs 100 and internal ribs 98, external ribs 100 providerigidity and strength to the portions of drive shaft 36 that do notinclude internal ribs 98. Furthermore, additional driving force may beexerted on drive shaft 36 because external ribs 100 facilitate torquetransfer to endless track 16 as further described herein.

First and second ends 94, 96 of the drive shaft assembly each includescoupling portions 102, 104, respectively. Coupling portions 102, 104 maybe machined or otherwise formed in first and second ends 94, 96 suchthat a lip 106 is formed between interior portion 90 and couplingportions 102, 104. Internal ribs 98 do not overlap coupling portions102, 104, however, external ribs 100 may overlap coupling portions 102,104.

First end 94 of drive shaft 36 couples with first end cap 108 that isreceived within coupling portion 102. First end cap 108 includes acomplementary coupling portion 110 that supports teeth 112. Inparticular, teeth 112 couples with splines 72 of lower sprocket 50 ofbelt drive assembly 34. As such, the rotation of lower sprocket 50rotates drive shaft 36 through teeth 112. First end cap 108 may becomprised of forged steel, for example, or other similar materials.

Second end 96 of drive shaft 36 couples with second end cap 118 that isreceived within coupling portion 104. Second end cap 118 includes acomplementary coupling portion 120 and a shaft member 122. Inparticular, shaft member 122 couples with frame 12, specificallybulkhead member 186 a, to support drive shaft 36. Second end cap 118 maybe comprised of cast aluminum, for example, or other similar materials.

Similar to drive shaft 36, first and second end caps 108, 118 arehexagonal in cross-section. First and second end caps 108, 118 may bepress fit within coupling portions 102, 104, respectively, in order toadhesively bond complementary coupling portions 110, 120 and couplingportions 102, 104.

Still referring to FIG. 15, the connections between complementarycoupling portions 110, 120 and respective coupling portions 102, 104define adhesive cavities 114. Adhesive cavities 114 are axially boundedon one end by lip 106. Illustratively, adhesive cavities 114 include twoadhesive ports 116, which increase the uniformity of the adhesive withinadhesive cavity 114. Alternative embodiments of adhesive cavities 114may include one adhesive port 116, or three or more adhesive ports 116.In one embodiment, mechanical fasteners (not shown) also are used tocouple first and second end caps 108, 118 to drive shaft 36.

The dimensions of adhesive cavities 114 correlates to the thickness ofadhesive in adhesive cavities 114, which determines the strength of thejoint formed by the adhesive, as further detailed in U.S. PatentApplication Publication No. 2011/0139528, filed on Feb. 14, 2011, thecomplete disclosure of which is expressly incorporated by referenceherein. If the thickness of the adhesive in adhesive cavities 114 is toothin, the resulting joints formed by coupling portions 102, 104 andcomplementary coupling portions 110, 120 may be weak. If the thicknessof the adhesive is too great, the resulting joint may not properlytransfer the load on drive shaft 36. In one embodiment of theillustrative drive shaft assembly, the surface of coupling portions 102,104, and complementary coupling portions 110, 120 are treated prior tobonding. Exemplary surface preparations or treatments include a dry ragwipe, a solvent degrease, a vapor degrease, a mechanical abrasion of thesurface, plasma treatment, chemical etching, and anodizing.

The adhesive may be an acrylic adhesive, for example. Exemplary acrylicadhesives are available from Lord Corporation. In one embodiment, theadhesive is combined with an accelerator to promote the curing of theadhesive. The curing time of the adhesive may be accelerated by applyingheat during the curing process (e.g., induction heat). In oneembodiment, the set time of the adhesive is approximately 20 minutes andthe cure time of the adhesive within adhesive cavities 114 isapproximately two hours at room temperature.

The drive shaft assembly may be comprised of dissimilar materials. Forexample, drive shaft 36 and second end cap 110 may be comprised ofaluminum. First end cap 108 may be comprised of forged steel. Adhesiveallows dissimilar materials to be joined, which also allows the use ofmaterials which are best suited for the operation of the drive shaftassembly. Additionally, certain welding methods, such as spot welding,may not be used to weld dissimilar metals and, as such, may not be usedto assemble drive shaft 36. Further, adhesive distributes the load incoupling portions 102, 104 over an area rather than concentrating it ata point or a line as is the case with rivets and welds. Localized stressconcentrations formed by drilled holes and welds may adversely affectthe material properties, such as fatigue strength. However, adhesivedoes not adversely affect the fatigue life or strength of the driveshaft assembly. Additionally, welding may cause an imbalance in thedrive shaft assembly. However, by using adhesive, the drive shaftassembly may be balanced.

It may be appreciated that the configuration and material composition ofthe drive shaft assembly contributes to an overall weight reduction ofsnowmobile 10. More particularly, lightweight materials, such asaluminum and adhesive, reduce the weight and rotational inertia of thedrive shaft assembly. Additionally, the substantially hollowconfiguration of drive shaft 36 further reduces the weight of the driveshaft assembly. Therefore, the weight of snowmobile 10 is reduced. Byreducing the overall weight, snowmobile 10 may roll and tilt onto itsside more easily, thereby requiring less effort from a rider to maneuversnowmobile 10. For example, illustrative snowmobile 10 may weighapproximately 419 pounds. Furthermore, by assembling the drive shaftassembly with dissimilar metals and adhesive, torque transfer mayimprove and additional driving torque may be exerted on the drive shaftassembly. It is to be understood that other shafts or components ofsnowmobile 10 may be similarly constructed (e.g., jackshaft 38).

Referring to FIG. 16, the drive shaft assembly may support endless track16 on drive sprockets 124. Drive sprockets 124 slide onto externalsurface 92 of drive shaft 36 and are press fit to external ribs 100.Endless track 16 rotates with drive shaft 36 on drive sprockets 124 inorder to move snowmobile 10. As mentioned above, external ribs 100 areprovided on drive shaft 36. Ribs 100 engage within slots 125 on drivesprockets 124 to assist in torque transfer (FIG. 5).

Referring to FIGS. 17-19, in addition to endless track 16, front skis 14facilitate the movement of snowmobile 10. More particularly, front skis14 include right ski 14 a and left ski 14 b, which are operably coupledto front suspension assembly 18. Front suspension assembly 18 includesright suspension 18 a and left suspension 18 b, each of which includes alower control arm 126, an upper control arm 128, a linear force element,illustratively a shock absorber 130, and a spindle 132. Front frameportion 12 a is coupled to skis 14 through front suspension assembly 18.

Lower and upper control arms 126, 128 of both right and left suspensions18 a, 18 b are operably coupled to spindles 132 through moveable joints134 and 200, respectively. Moveable joints 134, 200 may be secured tospindles 132 with mechanical fasteners 136, 198, respectively.Illustratively, joints 134, 200 are ball joints and mechanical fasteners136, 198 may be bolts (FIG. 18), although other embodiments of moveablejoints and mechanical fasteners may be used.

Lower control arms 126 include coupling members 138, which couple afirst arm 140 and a second arm 142 to joints 134 and to each other, asshown in FIGS. 20A and 20B. Additionally, shock absorbers 130 may extendthrough upper control arms 128 and are pivotally coupled to lowercontrol arms 126 via coupling members 138. As best shown in FIG. 20B,shock absorber 130 includes coupling portion 131, which may bethreadedly coupled to coupling member 138. In particular, couplingmember 138 may be cast or otherwise formed to include extensions 137 a,137 b. Extensions 137 a, 137 b receive a fastener, illustratively a bolt141, through openings 139 a, 139 b, respectively. Opening 139 b isinternally threaded such that the threaded end of bolt 141 is receivedwithin and threadedly coupled to extension 137 b. As such, bolt 141 maybe threadedly connected to front suspension 18 without the use of a nutor other fastening member.

Referring to FIG. 20A, first arm 140 includes a first end 140 a and asecond end 140 b, and second arm 142 includes a first end 142 a and asecond end 142 b. First ends 140 a, 142 a of respective first and secondarms 140, 142 are coupled to coupling member 138 while second ends 140b, 142 b are coupled to bearing members 144. Bearing members 144 couplefirst and second arms 140, 142 to front frame portion 12 a, as furtherdetailed hereinafter.

First and second arms 140, 142 are bonded to coupling member 138 andbearing members 144 with an adhesive material, such as those availablefrom Lord Corporation and detailed herein. In one embodiment, mechanicalfasteners (not shown) also are used to couple first and second arms 140,142 to coupling member 138 and bearing members 144. By using adhesive,welding is not required to assemble lower control arms 126.

When first ends 140 a, 142 a are inserted into coupling member 138, anadhesive cavity 146 is defined, as illustrated in FIG. 21B. Couplingmember 138 may include a recess 150 (FIG. 21A) that defines at leastthree boundary surfaces 150 a, 150 b, 150 c of adhesive cavity 146.Coupling member 138 illustratively includes two adhesive ports 148 foruniformly applying the adhesive. More particularly, the adhesive isapplied to adhesive cavity 146 in shear. Specifically, first and secondarms 140, 142 are slidably received within coupling member 138 when theadhesive is applied in order to bond and cure the adhesive in shear.Shear is the strongest loading mechanism and, therefore, sufficientlyassembles lower control arm 126 for snowmobile applications.

Adhesive cavity 146 may be treated or prepared before the adhesive isapplied therein. Exemplary surface preparations include a dry rag wipe,a solvent degrease, a vapor degrease, a mechanical abrasion of thesurface, plasma treatment, chemical etching, and anodizing. First andsecond arms 140, 142 also may be adhesively bonded with bearing members144 according to the same illustrative method. Additionally, alternativeembodiments of the present disclosure may adhesively bond upper controlarms 128 according to the illustrative method.

Lower control arms 136 may be comprised of dissimilar materials. Forexample, the illustrative embodiment of first and second arms 140, 142are comprised of high-strength, thin wall materials, such asnon-weldable aluminum, heat-treated steel, and/or carbon fibermaterials. Coupling member 138 and bearing members 144 may be comprisedof high-strength aluminum or plastic. Unlike certain welding methods(e.g., spot welding, adhesive may be used to join dissimilar materials.Additionally, welding may cause portions of lower control arms 126 to bethicker than is required for front suspension assembly 18 and increasethe weight of front suspension assembly 18. Furthermore, welding maycause fatigue scatter, distortion, and variations in lower control arms126 due to concentrated areas of stress formed during the weldingprocess. As such, welding may affect the fatigue strength and life oflower control arm 26. Conversely, adhesive distributes the load in lowercontrol arms 126 over an area rather than concentrating it at a point ora line as is the case with welds. As such, adhesive does not adverselyaffect the fatigue life and strength of lower control arms 126.

As shown in FIGS. 17, 19, and 22, front suspension assembly 18 iscoupled to front frame portion 12 a via right and left castings 188, 190of bulkhead 186. Specifically, upper and lower control arms 128, 126 arecoupled to right and left castings 188, 190 through bearing members 196,144 and conventional fasteners 193, 192, respectively. As shown in FIG.9, right and left castings 188, 190 are positioned forward of bulkheadmembers 186 a, 186 b, and more particularly, forward of engine cradle 40and are coupled thereto with a plurality of conventional fasteners, suchas bolts. Right and left castings 188, 190 also are coupled to eachother through a plurality of conventional fasteners 194. Right and leftcastings 188, 190 may be formed through conventional casting processesand are generally mirror images of each other. Right and left castings188, 190 each may include a housing 195 to prevent snow and ice fromentering front frame portion 12 a.

Referring to FIGS. 23 and 24, an overstructure 202 of front frameportion 12 a is coupled to right and left castings 188, 190.Overstructure 202 includes a cast coupling or connector 152 that isconfigured to attach plural frame tubes, specifically front frame tubes154, 156 and rear frame tubes 158, 160, thereto. Overstructure 202further comprises a lower frame tube 208 coupled to front frame tubes154, 156, as detailed herein.

An upper portion of frame tubes 154, 156, 158, 160 may be attached toconnector 152 by way of fasteners 162, and/or may be adhesively fixed toconnector 152. As shown, connector 152 further includes two support webs164, 166. Each support web 164, 166 has threaded apertures 168, 170 forcoupling an upper steering post 172 of steering assembly 26 to supportwebs 164, 166.

With reference to FIGS. 23 and 24, connector 152 further includes afirst circular channel 174 (FIG. 24) defined by portions 174 a, 174 bhaving threaded bosses 176 extending downwardly therethrough. A secondcircular channel 178 is defined by portions 178 a, 178 b having threadedbosses 180 extending downwardly. Circular channels 174, 178 areintersected by respective first and second cylindrical members 182 and184. It should be appreciated that the upper portions of front frametubes 154, 156 are positioned across first and second circular channels174, 178 and secured with fasteners 162 extending through frame tubes154, 156 and into threaded bosses 176, 180. Adhesive may also beapplied. The upper portions of rear frame tubes 158, 160 are positionedin first and second cylindrical members 182, 184 and may also be securedwith fasteners 162 and adhesive. As shown in FIG. 7, a lower portion ofrear frame tubes 158, 160 may be coupled to rear frame portion 12 b ofsnowmobile 10.

Front frame tubes 154, 156 may include stiffening inserts 224, 226,respectively (FIG. 24). Stiffening inserts 224, 226 are received withinthe upper portion of front frame tubes 154, 156. Stiffening inserts 224,226 are coupled to front frame tubes 154, 156 with fasteners 162.Additionally, shaped spacers, illustratively washers 228, 230, also arecoupled to front frame tubes 154, 156 with fasteners 162. Washers 228,230 are positioned intermediate front frame tubes 154, 156 and fasteners162. Stiffening inserts 224, 226 and washers 228, 230 provide structuralintegrity and generally reinforce front frame tubes 154, 156 whenfasteners 162 are coupled with threaded bosses 176, 180. In particular,washers 228, 230 and stiffening members 224, 226 prevent deformation ofthe upper portions of front frame tubes 154, 156 when fasteners 162 arecoupled with threaded bosses 176, 180 and tightened against front frametubes 154, 156.

A lower portion of front frame tubes 154, 156 may be coupled to aplurality of couplers 204, 206, respectively. Illustrative couplers 204,206 also are coupled to lower frame tube 208. Front frame tubes 154, 156may be angled relative to lower frame tube 208, such that front frametubes 154, 156 and lower frame tube 208 illustratively form a triangle.

The various connections within overstructure 202 may be made bytraditional mechanical couplings such as bolts, welds, rivets, screws,and other types of fasteners. In one embodiment, at least a portion ofthe connections of overstructure 202 are made with a structuraladhesive. Illustratively, front frame tubes 154, 156 and lower frametube 208 are bonded to couplers 204, 206 with structural adhesive, asfurther detailed herein.

Referring to FIGS. 25 and 26, front frame tube 154 and coupler 204cooperate to define an adhesive cavity 212. Adhesive cavity 212 isdefined when front frame tube 154 slides into coupler 204. Front frametube 154 and coupler 204 may also be secured together by mechanicalfasteners 218 which are received through openings 220 in coupler 204. Inone embodiment, fasteners 218 are self piercing rivets which piercethrough coupler 204 and secure the location of coupler 204 relative tofront frame tube 154.

In the illustrative embodiment, adhesive cavity 212 circumscribes frontframe tube 154. As illustrated, adhesive cavity 212 includes two ports214 into which the adhesive may be introduced for more uniform fillingof adhesive cavity 212 with the adhesive. In an alternative embodiment,a single adhesive port 214 is provided. In other alternativeembodiments, three or more adhesive ports 214 are provided. The volumeof adhesive cavity 212 is predetermined such that a predetermined amountof the adhesive is injected into adhesive cavity 212. The thickness ofthe adhesive is proportional to the strength of the connection betweenfront frame tube 154 and coupler 204. If the thickness is too thin, theresulting connection may be undesirably weak. If the thickness is toogreat, the resulting connection may not properly transfer the loadexerted on overstructure 202.

While the illustrative embodiment has been described with reference tofront frame tube 154 and coupler 204, it is to be understood that frontframe tube 156 is bonded to coupler 206 according to the illustrativemethod. Similarly, lower frame tube 208 is bonded to couplers 204, 206according to the illustrative method. The surfaces of front frame tubes154, 156 and lower frame tube 208 may be treated prior to assembly withcouplers 204, 206. Exemplary surface preparations or treatments includea dry rag wipe, a solvent degrease, a vapor degrease, a mechanicalabrasion or scuff of the surface, plasma treatment, chemical etching,and anodizing.

The adhesive may be an acrylic adhesive, for example, such as thosedescribed herein and available from Lord Corporation. In one embodiment,the adhesive is combined with an accelerator to promote the curing ofthe adhesive. The set time of the adhesive may be approximately 20minutes and the cure time of the adhesive may be approximately two hoursat room temperature. The cure time of the adhesive may be furtheraccelerated by applying heat during the curing process (e.g., inductionheat).

The illustrative embodiment of overstructure 202, and in particular,front frame tubes 154, 156, lower frame tube 208, and couplers 204, 206,includes dissimilar materials. For example, front frame tubes 154, 156are comprised of carbon fiber materials, although other high-strength,thin wall materials, such as high-strength, non-weldable aluminum andcertain steels may also be used. Similarly, lower frame tube 208 may becomprised of a carbon fiber material. The carbon fiber material may becoated with a plastic material to prevent a reaction with couplers 204,206, which are formed of various metal materials, such as aluminum orsteel.

Unlike welding, adhesive is able to bond dissimilar materials.Furthermore, welding may cause localized stress concentrations thataffect material fatigue strength and fatigue life. However, adhesivedistributes the load in overstructure 202 over an area, rather thanconcentrating it at a point or a line, and, therefore, does notadversely affect material properties. Additionally, compared to welds,the adhesive and carbon fiber of overstructure 202 reduces the weight ofoverstructure 202, and therefore, the weight of snowmobile 10, whichallows a rider easier maneuvering of snowmobile 10.

Referring to FIGS. 23 and 24, connector 152 includes machined mountingsurfaces 164A and 166A on the backside of support webs 164, 166,respectively, for mounting upper steering post 172 thereto, as isdescribed in U.S. Patent Application Publication No. 2011/0192667, filedon Feb. 4, 2011, the disclosure of which is expressly incorporated byreference herein. Steering assembly 26 further comprises a lowersteering post 232 operably coupled to upper steering post 172 viarespective links 234, 236. Links 234, 236 are connected together by wayof a drag arm 238. Ball joints 235 are coupled to drag arm 238 and links234, 236 to provide pivot points between drag arm 238 and links 234,236. Lower steering post 232 is connected to tie rods or steering rods240 (FIG. 3) by way of a follower arm 242 (FIG. 27) in order to maneuverskis 14. Moveable joints, illustratively ball joints 262, may be used topivotally couple follower arm 242 to steering rods 240. Steering rods240 may be positioned through housings 195 of castings 188, 190.

With reference to FIGS. 28 and 29, a support member 246 and a brace tube248 may be coupled to right and left castings 188, 190 to supportsteering assembly 26. More particularly, support member 246 is coupledto right casting 188 and brace tube 248 to support follower arm 242 andsteering rod 240 on the right side of snowmobile 10. Illustrative bracetube 248 is coupled to both right and left castings 188, 190 and extendstherebetween. More particularly, brace tube 248 may be coupled to theinner surfaces of right and left castings 188, 190 between bearingmembers 196 of upper control arms 128. Brace tube 248 may be comprisedof lightweight, high-strength materials, such as carbon fiber. As such,brace tube 248 may lower the weight of snowmobile 10.

Referring to FIGS. 19, 27, and 29-31, steering rods 240 are operablycoupled to spindles 132 and follower arm 242 through ball joints 262.Steering rods 240 include an arm 266 coupled to brackets 268. Moreparticularly, and as best shown in FIG. 30, brackets 268 are coupled toboth a first end 276 of arm 266 and a second end 278 of arm 266.Brackets 268 are illustratively coupled to arm 266 with adhesive. In oneembodiment, mechanical fasteners (not shown) may also be used to couplebrackets 268 to arm 266.

As shown in FIGS. 30 and 31, brackets 268 include a recess 272 thatdefines an adhesive cavity 274 when brackets 268 are coupled to arm 266.In particular, adhesive cavity 274 is bounded on three sides by surfaces272 a, 272 b, 272 c of recess 272 and is further defined by arm 266. Arm266 includes adhesive ports 280 for receiving adhesive into adhesivecavity 274. As detailed above with respect to other components ofsnowmobile 10, adhesive is applied in a predetermined volume thatcorresponds to the volume of adhesive cavity 274. The adhesive may be astructural adhesive available from Lord Corporation and may be used withan accelerator. The adhesive is applied in shear when brackets 268 arereceived within first and second ends 276, 278 of arm 266.

Additionally, in one embodiment of the present disclosure and shown inFIG. 27, drag arm 238 includes an arm member 237 and brackets 239, asshown in FIGS. 32A and 32B. Brackets 239 slidingly receive ball joints235. Brackets 239 of drag arm 238 include a recess 264 that defines anadhesive cavity 265 when brackets 239 are received within arm member237. Drag arm 238 may be assembled with adhesive through adhesive ports241 according to the illustrative method.

The use of the adhesive to assemble drag arm 238 and steering rods 240,may replace other conventional joining methods (e.g., welding). Unlikewelding, the adhesive does not form localized areas of stress at theconnection points of drag arm 238 and steering rods 240. Furthermore,the adhesive allows dissimilar metals to be joined, which may reduce theweight of snowmobile 10. Additionally, by eliminating welds on drag arm238 and steering rods 240, the weight of steering assembly 26 isreduced.

Referring to FIG. 32A, ball joints 235 include threaded posts 216, whichare received within threaded apertures of brackets 239 of drag arm 238and secured thereto with a fastener, such as a nut 217. Similarly, balljoints 262 include a threaded post 267, which is received withinthreaded apertures of brackets 268 and secured thereto with a fastener,such as nut 269. Nuts 217, 269 may be threadedly coupled to posts 216,267 to secure ball joints 235, 262, respectively.

As shown in FIGS. 33A and 33B, handlebars 250 of steering assembly 26are attached to upper steering post 172 by way of a clamp 252.Illustratively, handlebars 250 a, 250 b each include a bend 550 a, 550b, respectively, and each extend therefrom in a generally horizontaldirection and are generally perpendicular to upper steering post 172.Handlebar 250 a includes an auxiliary power button 254 and a throttlehandle 255. Handlebar 250 b includes a brake lever 258. Auxiliary powerbutton 254 is coupled to handlebar 250 a through a base 256 and a clamp260. Auxiliary power button 254 may be snapped into base 256, ratherthan secured thereto with a mechanical fastener. Clamp 260illustratively extends around handlebar 250 a in a U-shape or C-shapeconfiguration and may be secured with a mechanical fastener 261 (e.g.,screw, bolt). Other clamping or mounting mechanisms that do not requirethe use of a mechanical fastener also may be used to couple auxiliarypower button 254 to handlebar 250 a.

Auxiliary power button 254 is vertically oriented on handlebar 250 a.More particularly, the orientation of auxiliary power button 254 isgenerally parallel to upper steering post 172 and generallyperpendicular to handlebars 250. The vertical orientation of auxiliarypower button 254 prevents the rider from accidentally bumping auxiliarypower button 254 and unintentionally turning off engine 28. Furthermore,auxiliary power button 254 is spaced apart from throttle handle 255,which also prevents a rider from unintentionally depressing auxiliarypower button 254 when adjusting throttle handle 255. Illustratively,auxiliary power button 254 is positioned on bend 550 a.

With reference to FIG. 33C, one embodiment of steering assembly 26 mayinclude substantially horizontal handlebars 250 a′ and 250 b′, clamp252′, and auxiliary power button 254′. Substantially horizontalhandlebars 250 a′, 250 b′ are coupled to clamp 252′ and extend outwardlytherefrom. As such, clamp 252′ is intermediate substantially horizontalhandlebars 250 a′ and 250 b′, and may be vertically and horizontallyaligned therewith. Unlike handlebars 250, substantially horizontalhandlebars 250′ do not include bends 550 a, 550 b. Similar to handlebar250 b, substantially horizontal handlebar 250 b′ includes brake lever258. Illustratively, auxiliary power button 254′ is coupled tosubstantially horizontal handlebar 250 a′ and is adjacent throttlehandle 255. More particularly, auxiliary power button 254′ snaps onto,or is otherwise coupled to, handlebar 250 a′ in a substantially verticalorientation via clamp 260. Clamp 260 may be secured to substantiallyhorizontal handlebar 250 a′ with a fastener (not shown). Additionally,auxiliary power button 254′ may be coupled to substantially horizontalhandlebar 250 a′ without base 256.

Referring to FIGS. 17 and 19, front frame portion 12 a further include atorsion bar or sway bar 282 coupled to the front of right and leftcastings 188, 190. Sway bar 282 is supported by clamps 284 extendingfrom right and left castings 188, 190. Rubber isolators or bushings 286may be positioned within clamps 284 to allow sway bar 282 to pivotwithin clamps 284. Sway bar 282 extends across the front of right andleft castings 188, 190 and bends rearwardly toward lower controls arms126. Illustratively, sway bar 282 is coupled to lower control arms 126through a link arm 288 and a bracket 290. More particularly, a first end292 of link arm 288 includes an aperture 294 that receives sway bar 282.A second end 296 of link arm 288 is coupled to bracket 290 withfasteners 298.

Bracket 290 includes an opening 300 and extensions 302. Opening 300 issized to receive arm 140 of lower control arm 126. Extensions 302 arespaced apart such that second end 296 of link arm 288 is positionedtherebetween. Fastener 298 is received through apertures (not shown) inextensions 302 and second end 296 of link arm 288. Link arm 288 isconfigured to pivot about fastener 298 in response to movement of frontsuspension 18.

Referring to FIGS. 34-36, rear frame portion 12 b includes tunnel 39,rear suspension assembly 20, a running board assembly 304, and endlesstrack 16. Tunnel 39 includes a top wall 308, a front wall 312, sidewalls 310, and a rear end 350. Front wall 312 extends between jackshaft38 and drive shaft 36 such that drive shaft 36 is positioned withintunnel 39 and jackshaft 38 is positioned outside of tunnel 39.

As shown in FIGS. 38 and 43, side walls 310 are removably coupled to topwall 308 of tunnel 39 with fasteners 311, which may embody rivets,bolts, adhesive, screws, or any combination thereof. Side walls 310include a plurality of apertures 402 to reduce the weight of side walls310, thereby further reducing the overall weight of snowmobile 10.Similarly, tunnel 39 may include a plurality of apertures 403, whichalso reduce the weight of snowmobile 10. Side walls 310 extend fromfront wall 312 to rear end 350, as shown in FIG. 50. Side walls 310 maybe comprised of lightweight, high-strength materials such as aluminum,steel, or other similar materials.

Top wall 308 of tunnel 39 includes lateral portions 314 and a centerportion 316. Lateral portions 314 illustratively include recessedchannels 318 (FIG. 38) configured to receive fasteners 366 (e.g., bolts)for mounting accessories onto top wall 308 of tunnel 39. For example,fasteners may slide into recessed channels 318 in order to secure cargoor a cargo carrying unit to top wall 308.

As shown in FIG. 43, an electrical cover 342 may be positioned alongcenter portion 316 of top wall 308 and intermediate recessed channels308. Electrical cover 342 extends rearwardly from seat assembly 20 andtoward rear end 350 of tunnel 39. More particularly, electrical cover342 is coupled to a socket 344 (FIG. 35), which is configured to securea brake light (not shown) or other illumination or electrical device tosnowmobile 10. Electrical cover 342 is coupled to top wall 308 and isconfigured to accommodate electrical wires (not shown) therein.

As shown in FIGS. 35 and 36, adjacent socket 344 is a snow flap 346 anda rear bumper 348. Snow flap 346 is hingedly mounted to the tunnel 39along rear end 350. Snow flap 346 includes a plurality of apertures 352to reduce the weight of snow flap 346, thereby further decreasing theoverall weight of snowmobile 10. Apertures 352 may be machined or moldedin snow flap 346.

Referring to FIGS. 26 and 35, tunnel 39 may further include heatexchanger channels (not shown) positioned forward of electrical cover342, as more fully described in U.S. Pat. No. 7,870,920, issued on Jan.18, 2011, the disclosure of which is incorporated by reference herein.The heat exchanger channels may be positioned along the underside oftunnel 39 and below seat assembly 22. Top wall 308 of tunnel 39illustratively includes fluid ports 338 (FIG. 43) that are fluidlycoupled to heat exchanger channels and engine 28. In operation, enginewater may flow from engine 28 to a port 338 through a hose (not shown)and circulate through the heat exchanger channels in order to cool theengine water. Cooled engine water exits through the other port 338 andflows toward engine 28 in a second hose (not shown). During operation ofsnowmobile 10, snow and ice are kicked up toward the heat exchangerchannels, which cools the engine water. Top wall 308 may includeinsulation panels 340 to isolate the heat exchanger channels from therider and/or other components of snowmobile 10 (FIG. 50).Illustratively, there are six insulation panels 340. Insulation panels340 may be comprised of foam or other insulation material.

As shown in FIGS. 35-38 and 43-46, running board assembly 304 is coupledto side walls 310 of tunnel 39 and includes a foot tread assembly 384and a toe grip assembly 400. Foot tread assembly 384 includes runningboard plates 390 and a plurality of support members, illustratively abracket 394 and an elbow 396. Running board plates 390 include plateportion 408 and elongate member 388. Foot tread assembly 384 isremovably coupled to side walls 310 with fasteners 412 and 440.Additionally, foot tread assembly 384 is removably coupled to toe gripassembly 400 with fasteners 406. Fasteners 406, 412, and 440 may beconventional fasteners, such as bolts, rivets, and screws to facilitateremoval of food tread assembly 384 from snowmobile 10. As such, foottread assembly 384 may be easily replaced, repaired, or otherwiseserviced, without replacing or disassembling side walls 310, tunnel 39,or other portions of snowmobile 10.

With respect to FIG. 43, plate portion 408 is comprised of a pluralityof openings 418 that extend from elongate member 388 to a marginal edge410 of running board plate 390. As such, openings 418 extendsubstantially across the width of running board plate 390 to provide amaximum open area on plate portion 408 for snow to fall through. Thebottom surface of running board plates 390 is substantially smooth,which also facilitates snow removal from plate portion 408. Grippingserrations 424 on plate portion 408 and elongate member 388 providetraction for a rider's foot. Illustratively, gripping serrations 424border or outline openings 418. Openings 418 may be embossed to rigidifyplate portion 408.

Running board plate 390 may be extruded as a single piece, such thatplate portion 408, gripping serrations 424, elongate member 388, andmarginal edge 410 are integrally formed. In one embodiment, openings 418and marginal edge 410 are machined through conventional methods. Runningboard plates 390 may be extruded and machined from high-strengthaluminum. As such, running board plates 390 are comprised of alightweight material that may contribute to an overall weight reductionof snowmobile 10.

As shown in FIGS. 37 and 43-46, bracket 394 may be removable fromelongate member 388 and is formed through conventional casting methods.Elongate member 388 extends in a generally parallel direction tolongitudinal axis L of snowmobile 10 and includes an internal web 416.With particular reference to FIGS. 45 and 46, bracket 394 includes abracket body 398 having a first coupling portion 399 a extending intoelongate member 388 and a second coupling portion 399 b for attachmentto a flange 404 of toe grip assembly 400. First coupling portion 399 aextends in the same direction as elongate member 388. Second couplingportion 399 b is angled relative to first coupling portion 399 a andextends in at least a partially vertical direction.

First coupling portion 399 a of bracket body 398 may be attached toelongate member 388 by way of fasteners 426, such as bolts, screws,welds, rivets, adhesives, or a combination thereof. More particularly,relative to bracket body 398, first coupling portion 399 a has a reducedcross section corresponding to the inner diameter of elongate member 388for receipt therein. First coupling portions 399 a include slots 414 toreceive internal web 416 of elongate member 388.

Illustratively, first coupling portion 399 a is coupled to elongatemember 388 with adhesive and fasteners 426. In particular, as shown inFIGS. 45 and 46, frame bracket 394 includes opposing adhesive cavities395 and adhesive ports 397 that are separated by slots 414 and internalweb 416 of elongate member 388. The reduced cross-section of firstcoupling portion 399 a defines recesses 401 having surfaces 401 a, 401b, 401 c that cooperate with internal web 416 to define adhesivecavities 395. When first coupling portion 399 a slides into elongatemember 388, adhesive is injected through adhesive ports 397 intoadhesive cavities 395 in a predetermined volume such that the thicknessof the adhesive is known. The strength of the connection between framebracket 394 and elongate member 388 corresponds to the thickness of theadhesive and is further increased when the adhesive is in shear. Surfacetreatments may be used to prepare adhesive cavities 395, as detailedherein.

Referring to FIGS. 36 and 43, flange 404 couples second coupling portion399 b of frame bracket 394 to a toe grip assembly 400. Illustratively,flange 404 and second coupling portion 399 b are positioned back-to-backand attached by way of fasteners 406. Second coupling portion 399 b hasa flattened cross-section which is similar to that of flange 404.

Referring to FIGS. 45A-46B, elbow 396 includes a first coupling portion432 and a second coupling portion 434. Elbow 396 extends upwardly in agenerally diagonal direction to couple elongate member 388 to side wall310. Elbow 396 is positioned at the opposite end of elongate member 388relative to bracket 394 and supports running board plate 390 near rearportion 350 of tunnel 39. More particularly, second coupling portion 434of elbow 396 is opposite first coupling portion 432 and couples elbow396 to side wall 310 with a fastener 440. Illustratively, only fastener440 couples elbow 396 to side wall 310, however, other embodiments ofthe present disclosure may use more than one fastening member. Secondcoupling portion 434 illustratively includes a plurality of apertures439, which may reduce the weight of elbow 396 and, therefore, reduce theweight of snowmobile 10. Additionally, apertures 439 may facilitate snowremoval from foot tread assembly 384.

As shown in FIGS. 45B and 46B, first coupling portion 432 of elbow 396has a reduced cross-section and includes slots 436 to receive internalweb 416 of elongate member 388. As such, first coupling portion 432 isreceived within elongate member 388 and is coupled thereto withfasteners 438. In one embodiment, elbow 396 is bonded to elongate member388 with adhesive. In particular, first coupling portion 432 includesadhesive cavities 433 and adhesive ports 435 to receive adhesive intoadhesive cavities 433. Adhesive cavities 433 and ports 435 are onopposing sides of first coupling portion 432 and are separated by slots436 and internal web 416 of elongate member 388. The reducedcross-section of first coupling portion 432 defines recesses 437. Inparticular, surfaces 437 a, 437 b, 437 c of recesses 437 cooperate withinternal web 416 to define adhesive cavities 433 when first couplingportion 432 slides into elongate member 388. Adhesive is injectedthrough adhesive ports 435 into adhesive cavities 433 in a predeterminedvolume such that the thickness of the adhesive is known. The strength ofthe connection between elbow 396 and elongate member 388 correlates tothe thickness of the adhesive and is further increased by applying theadhesive in shear. Surface treatments may be used to prepare adhesivecavities 433, as detailed herein.

Unlike welding, adhesive may be used to bond bracket 394 and elbow 396to elongate member 388. As such, bracket 394 and elbow 396 may becomprised of different materials than elongate member 388. Additionally,welding may form areas of localized stress, which reduce the fatiguelife and strength of the material. However, adhesive does not causestress concentrations and does not adversely affect fatigue life andstrength. Additionally, adhesive may reduce the weight of elongate framemember 388, thereby further reducing the weight of snowmobile 10.Exemplary adhesives are available from Lord Corporation, as detailedherein. Induction heat and/or accelerators may be used to decreasecuring time of the adhesive in adhesive cavities 395, 433.

With reference now to FIGS. 35 and 36, toe grip assembly 400 includes ashroud (not shown), a back wall 444, a frame member 446, and a toe clip448, as further detailed in U.S. Patent Application Publication No.2011/0192667, filed on Feb. 4, 2011, the complete disclosure of which isincorporated by reference herein. Toe clip 448 is positioned rearward ofback wall 444 to secure a rider's foot. The shroud generally covers backwall 444 and at least a portion of toe clip 448.

Referring to FIGS. 39A-42, seat assembly 20 is coupled to top wall 308and includes a seat mount 320, a seat base 322, a cushion 324, a cover326, a bracket 328, and fasteners 330. Cover 326 may be comprised of awater-repellant fabric or polymeric material and wraps around cushion324. Seat base 322 and cushion 324 may be comprised of polymericmaterials, for example, polyurethane. In one embodiment of seat assembly22, seat base 322 is comprised of rigid polyurethane, whereas cushion324 is comprised of softer polyurethane foam. Cushion 324 and seat base322 may be comprised of similar polymers such that cushion 324 may bemolded to or otherwise bonded or coupled with seat base 322.Alternatively, seat base 322 may be comprised of other lightweightmaterials, for example aluminum.

As shown in FIGS. 40 and 41, the top surface 324 a of cushion 324 isgenerally flat and extends along a longitudinal axis L_(S) of cushion324. The sides 324 b, 324 c, 324 d, 324 e, 324 f, 324 g extenddownwardly from top surface 324 a and are generally slanted or angled.More particularly, sides 324 b, 324 c, 324 d are generally mirror imagesof sides 324 g, 324 f, 324 e, respectively, and are positioned onopposite sides of longitudinal axis L_(S). Relative to conventional seatcushions for snowmobiles, the height of cushion 324 may be reduced andthe width of cushion 324 may be increased because sides 324 b, 324 c,324 d, 324 e, 324 f, 324 g extend both outwardly and downwardly.

Referring to FIGS. 39B and 41, cushion 324 also includes a plurality ofvoids 325. Voids 325 may be arranged in rows extending across the widthof cushion 324, or otherwise distributed throughout cushion 324. Forexample, cushion 324 may include a plurality of rows having three voids325 each. Illustratively, voids 325 are generally circular incross-section but voids 325 may define other shapes in cross-section inother embodiments of seat assembly 22. Similarly, seat base 322 mayinclude a plurality of apertures 323. The position of apertures 323 maycorrespond to the general position of voids 325, however, apertures 323may positioned in other arrangements. Illustratively, apertures 323 havea generally polygonal shape, although apertures 323 may define othershapes (e.g., circle) in cross-section. The lightweight materialscomprising seat base 322 and cushion 324 (e.g., polymers) reduce theweight of seat assembly 22. Additionally, voids 325 of cushion 324 andapertures 323 of seat base 322 also reduce the weight of seat assembly22. As such, the weight of snowmobile 10 is reduced, which increases themaneuverability of snowmobile 10.

Referring to FIGS. 41 and 42, seat base 322 is coupled to seat mount 320through bracket 328 and fasteners 330. More particularly, fasteners 330extend through apertures 332 in seat base 322 and through apertures 334in seat mount 320 to support cushion 324 on tunnel 39. Fasteners 330 maybe bolts, screws, rivets, or other couplers that extend throughapertures 334 in seat mount 320 and couple with complementary fasteners336, such as nuts.

As shown in FIGS. 1B and 16, endless track 16 may be supported by drivesprockets 124 and rear suspension 20, as further detailed herein. Moreparticularly, endless track 16 extends from rear portion 350 to frontwall 312 of tunnel 39. Additionally, endless track 16 extends at leastpartially into tunnel 39 and extends below tunnel 39 to contact theground. The inner surface of endless track 16 is substantially flat andmoves smoothly over drive sprockets 124 and portions of rear suspension20.

As best shown in FIG. 52, the outer surface of endless track 16 includesa plurality of couplers 354 and a plurality of intermediate extensions355. Couplers 354 extend across a plurality of tread layers 357 suchthat couplers 354 extend substantially across the width of endless track16. Illustratively, endless track 16 includes four tread layers 357extending in a circumferential direction. Intermediate extensions 355are positioned in an alternating arrangement with couplers 354 and havea width less than the width of couplers 354. Each intermediate extension355 is supported by a tread member 359 that is perpendicular to treadlayers 357. As shown in FIG. 52, tread layers 354 intersect treadmembers 359 to define a plurality of apertures 353. Couplers 354 andintermediate extensions 355 project outwardly from tread layers 357 andtread members 359, respectively, to contact the ground. In oneembodiment, the height of couplers 354 is approximately equal to theheight of intermediate extensions 355. The width and height of couplers354 may provide improved travel over icy or frozen surfaces. Forexample, when snowmobile 10 is travelling over rutted snow or frozenterrain, couplers 354 may break through more of the surface ice andsnow.

Referring to FIG. 34, endless track 16 extends around rear suspensionassembly 20, which is attached to the inner surfaces of side walls 310.A frame 356 of rear suspension assembly 20 includes laterally spacedframe rails 358, slide rails 360 attached to frame rails 358, and idlerrollers 372, 374. Rear suspension assembly 20 also includes linear forceelements, illustratively two coil-over shocks 362 and 364, providingdampening between tunnel 39 and frame 356, front torque arms 376, reartorque arms 378, and a pull rod 380. Rear torque arms 378 are positionedrearward of shocks 362, 364 and are coupled to the inner surfaces ofidler rollers 372 and frame rails 358. Rear torque arms 378 also areoperably coupled to pull rod 380 and shock 364. Shock 362 is coupled tofront torque arms 376 and frame rails 358.

Referring to FIGS. 34A and 34B, front torque arms 376 are positionedintermediate shocks 362, 364 and an upper end 454 of front torque arms376 is coupled to the inner surface of side walls 310 and operablycoupled to shock 362. A lower end 456 of front torque arms 376 iscoupled to frame rails 358 and operably coupled to shock 364 and pullrod 380.

As best shown in FIG. 34B, upper end 454 of shock 364 is coupled tofront torque arms 376 with isolator members, illustratively bushings524, sleeve members 526 and 528, and a bearing member 530. Bushings 524are received within an aperture 532 of upper end 454 of shock 364, andinclude openings 525 to receive sleeve members 526, 528 and bearingmember 530. In particular, sleeve member 526 includes an opening 527 toreceive sleeve member 528. Similarly, sleeve member 528 includes anopening 529 to receive bearing member 530. As such, sleeve member 528 ispress fit around bearing member 530 to generally surround bearing member530. Sleeve member 528 and bearing member 530 are positioned withinsleeve member 526, which is press fit within bushings 524, in order tocouple shock 364 to front torque arms 376 of rear suspension 20. Sleevemembers 526, 528 may be comprised of metal, for example, sleeve member528 may be comprised of aluminum and sleeve member 526 may be comprisedof steel. Bearing member 530 and bushings 524 may be comprised of apolymeric material (e.g., rubber). The lightweight materials of shock364 may contribute to an overall weight reduction of snowmobile 10.

As shown in FIGS. 47A and 47B, front torque arms 376 include couplers458, 460, a shaft 462, wear guides 464, bushings 466, and arm members468. In particular, couplers 458 receive shaft 462 and upper ends 454 ofarm members 468. Couplers 460 receive lower ends 456 of arm members 468and bushings 466. Exemplary bushings 466 are available from Igus® GmbHand/or Igus® Inc. Rear torque arms 378 also may include arm members,couplers, and bushings. Similar to front torque arms 376, the couplersof rear torque arms 378 may receive bushings therethrough. Couplers 458,460 may be formed through conventional casting processes.

Couplers 458 are coupled to upper ends 454 of arm members 468, shaft462, and wear guides 464 with fasteners (not shown), such as bolts,screws, rivets, welds, adhesive, or a combination thereof. Inparticular, upper ends 454 of arm members 468 are received withincouplers 458 and are coupled thereto with adhesive. Similarly, shaft 462is received through couplers 458 and may be coupled thereto withadhesive. Additionally, lower ends 456 of arm members 468 are receivedwithin couplers 460 and are coupled thereto with adhesive.

As shown in FIGS. 47B and 48, couplers 458, 460 include a recess 470that defines an adhesive cavity 472 when arm members 468 slide intocouplers 458, 460. Adhesive cavity 472 is bounded by surfaces 470 a, 470b, 470 c of recess 470 and arm members 468. Additionally, couplers 458,460 include adhesive ports 474 through which the adhesive is injectedinto adhesive cavity 472. The adhesive may be applied in shear for astrong connection between couplers 458, 460 and arm members 468. Forexample, couplers 458, 460 and arm members 468 are bonded in shear whenarm members 468 slide into couplers 458, 460. It is to be understoodthat shaft 462 may be coupled to couplers 458 in the same mannerdetailed herein. Additionally, rear torque arm 378 may be similarlybonded.

Exemplary adhesive materials are available from Lord Corporation.Accelerators may be used to decrease the cure time of the adhesive andalso are available from Lord Corporation. Additionally, heat treatment,such as induction heating, may be used to further accelerate the curetime of the adhesive in adhesive cavity 472. Couplers 458, 460 and armmembers 468 may be treated or prepared for the adhesive, as detailedherein. A predetermined volume of adhesive, corresponding to the volumeof adhesive cavity 472, may be injected therein to ensure that thethickness of the adhesive at the connection between couplers 458, 460and arm members 468 is sufficient for the required strength of theconnection.

By using the adhesive, front torque arms 376 may be comprised ofdissimilar materials. For example, arm members 468 and shaft 462 may becomprised of heat-treated steel, high-strength aluminum, carbon fiber,and other materials with similar properties. Couplers 458 and wearguides 464 may be comprised of high-strength aluminum, polymericmaterials (e.g., ultra-high molecular weight polyethylene), and othermaterials with similar properties. Additionally, adhesive does notadversely affect material fatigue life and strength, or cause stressconcentrations. The adhesive in front torque arms 376 also reduces theweight of rear suspension assembly 20 and, therefore, the weight ofsnowmobile 10. It is to be appreciated that couplers 460 may be bondedin shear to lower ends 456 of arm members 468 according to theillustrative method described herein. Additionally, other components ofrear suspension assembly 20, such as rear torque arms 378, wear guides464, and shaft 462, may also be assembled with the adhesive material.

As shown in FIG. 34, idler rollers 372 are coupled to suspension pads476 and the inner surface of side wall 310. Additionally, suspensionpads 476 are coupled to the bottom surface of running board plates 390with fasteners. Suspension pads 476 include a first plate (not shown)and a second plate 480. More particularly, the first plate and secondplate 480 may be comprised of dissimilar materials, such as aluminum andsteel. Suspension pads 476 reinforce side walls 310 at the location ofidler rollers 372.

Referring to FIG. 49-51C, snowmobile 10 includes various electricalcomponents supported by frame 12. For example, as shown in FIGS. 49-50B,a regulator (not shown) is housed in a regulator cover 482 on aregulator mount 484. The regulator may be configured for both AC and DCapplications. Regulator cover 482 is positioned partially through anaperture 481 in regulator mount 484 and coupled to regulator mount 484with fasteners. Regulator mount 484 is illustratively positioned abovehousing 33 of clutch assembly 32. More particularly, regulator mount 484is adjacent an opening 480 in housing 33. Opening 481 of regulator mount484 receives fins 488 of regulator cover 482. Illustratively, fins 488extend in a generally downward direction from regulator mount 484 andare directed toward opening 480 in housing 33. In operation, air inhousing 33 of clutch assembly 32 flows through the opening in housing 33and toward fins 488, which receive the air from housing 33 to cool theregulator.

In an alternative embodiment of the present disclosure, bulkhead 186 orother components of front frame portion 12 a may be used as a heat sinkto cool the regulator. As such, regulator mount 484 may be coupled tobulkhead 186. Fins 488 also may be positioned to receive ambient airflowing through an opening (not shown) in the front outer body to coolthe regulator.

Referring to FIGS. 51A-51C, other electrical components of snowmobile 10may include a solenoid 510 and EV coils 512. EV coils 512 and solenoid510 may be supported by overstructure 202 of front frame portion 12 a,and coupled to engine 28 and other components of snowmobile 10.Illustratively, lower frame tube 208 may be coupled to a mounting member490 that supports EV coils 512 and solenoid 510 near the front ofsnowmobile 10. More particularly, mounting member 490 may be comprisedof a plastic material and bonded to lower frame tube 208 with adhesive.A mechanical scuff or other abrasion treatment may be used to preparelower frame tube 208 prior to bonding with mounting member 490.

The bottom surface of mounting member 490 may include a plurality ofribs 514 (FIG. 51B), which provide a textured surface to facilitate theadhesive bond between lower frame tube 208 and mounting member 490. Inparticular, the adhesive will be retained within the recessed portions516 between ribs 514. The adhesive may be applied through adhesive ports518 of mounting member 490 in the same illustrative manner describedherein. For example, a predetermined volume of adhesive may be appliedto mounting member 490 such that the thickness and, therefore, theeffectiveness, of the adhesive bond may be known and controlled.Furthermore, as best shown in FIG. 51C, mounting member 490 includes alocating tab 520 that fits within locating aperture 209 of lower frametube 208. Locating tab 520 cooperates with locating aperture 209 toposition mounting member 490 on lower frame tube 208 prior to applyingthe adhesive to bond mounting member 490 to lower frame tube 208. It isto be understood that mounting member 490 may be coupled to othercomponents of front frame portion 12 a, for example front frame tubes154, 156, according to the same illustrative method described herein.

Additionally, snowmobile 10 includes a display (not shown) to visuallyindicate the status of various operations and systems of snowmobile 10to a rider. For example, the display may be positioned below handlebars250 and may include a speed output and a fuel gauge. The fuel gaugecommunicates with a fuel resistor (not shown) to indicate the amount andtype of fuel being used by snowmobile 10. In one embodiment, snowmobile10 is configured to receive various types of fuel (e.g., ethanol,non-ethanol). The fuel gauge and fuel resistor may be configured tochange the type of fuel being used by snowmobile 10 without changing thefuel resistor. As such, the rider may be able to increase the fuelefficiency of snowmobile 10.

With reference now to FIGS. 53-59, another embodiment of the snowmobileis shown. In the second embodiment, as shown in FIGS. 54-59, thecomponents are substantially as disclosed in the snowmobile describedabove with respect to FIGS. 1-52, with the exceptions as provided below.The change to the embodiment of FIGS. 54-59 is that the snowmobile hasbeen modified to increase the clearance under the snowmobile for deepsnow. Before describing the embodiment of FIGS. 54-59, an existingsnowmobile, as depicted in FIG. 53 will be described.

The snowmobile as depicted in FIG. 53 is an existing snowmobile, and isApplicant's RMK model. As shown, the snowmobile has various componentswhich dictate the clearance underneath the snowmobile. For example, andstarting from the front of the snowmobile, distance 682 in the FIG. 53embodiment is the length of the spindle S from a ski bolt hole to alower ball joint of the A-arm. In this snowmobile, distance 682 is 4.91inches (124.66 mm). Moving rearwardly, the next relevant distance is thedistance is measured from a bottom of the engine cradle to a position tothe bottom 676 of the ski. In this embodiment, the distance 678 is 7.433inches (188.80 mm). Finally, the height of the snowmobile frame (and inparticular, tunnel T) in relation to the ground is influenced by therear suspension, and in particular the location of the point of rotationP of a front control arm C on the tunnel. In the embodiment of FIG. 53,the distance 684 is the distance from the bottom of the engine cradle tothe pivot point P on the tunnel, and is 5.3391 inches (135.613 mm).

With reference now to FIGS. 54 and 55, the main portions of thesnowmobile are shown at 602. Snowmobile 602 includes a frame 604including a tunnel 606 and a frame front portion 608. It should also beappreciated that snowmobile includes rear suspension 610 including suchitems as slide rails 612, carrier rollers 614, front control arms 616,rear control arms 618 and shock absorbers at 620. Tunnel 606 mayincorporate a cooling system for engine water as more fully described inour U.S. Pat. No. 7,870,920, the disclosure of which is incorporatedherein by reference.

Snowmobile 602 would also include a front suspension system shown at 626including lower control arms 628, upper control arms 630, a shockabsorber 632, and a spindle 634 attached to ski 636. Snowmobile framefront portion 608 may be similar to our US Publication number20110132679, the subject matter of which is incorporated herein byreference. Snowmobile 602 also includes a drive mechanism at 640 and asteering mechanism at 642.

As shown in FIG. 56, a lower body panel 650 is shown which extendsacross the bottom of the snowmobile and defines a front lower edgehaving the lowest front portion of the snowmobile chassis relative tothe ground (snow). FIG. 56 also shows the drive shaft 640 includingdrive sprockets 652, where drive sprockets 652 are positioned forward ofslide rails 612 and lower than body panel 650, as more fully describedherein. Given the above general description, the raised chassis portionof the snowmobile for deep snow 602 will now be described.

With reference to FIGS. 57 and 58, the front suspension 626 will bedescribed in greater detail as modified for the raised chassis. As shownbest in FIG. 57, lower control arm 628 is attached to bulkhead 608 atpivotal connections 660 whereas upper control arm 630 is attached tobulkhead 608 at pivotal connections 662. Meanwhile, lower control arm628 is attached to spindle 634 at ball joint 664 and upper control arm630 is attached to spindle at ball joint 666. Spindle 634 is attached toski 636 about a fastener 668.

With reference still to FIG. 57, a distance 680 is shown which is thedistance between the center of ball joint 664 (within spindle 634) tothe center of the fastener 668. As shown, and in a first embodiment,distance 680 is 6.91 inches (175.41 mm) whereas the analogous distance682 in the FIG. 53 embodiment is 4.91 inches (124.66 mm). Thus, thespindle has been raised by an additional two inches yet the suspensioncomponents, namely the lower control arm 628 and upper control arm 630are positioned in the same manner relative to the bulkhead and thespindle 634 as before; the length of the spindle has only changed from aposition downwardly from the connection point of the lower control arm628.

With respect to FIG. 59, the body panel 650 is positioned verticallyadjacent to a center line 670 of the driveshaft 640. In the embodimentshown, the distance from the body panel 650 to centerline 670 ispreferably less than one and a half inches and in the embodiment shownis 1.4 inches (31.64 mm). Furthermore, the bottom of the chassis 650 hasbeen raised relative to a lower outer portion of the drive sprocket 652.In the FIG. 53 embodiment, the bottom of the sprocket is essentiallyplanar with the bottom of the chassis, such that distance 674 isapproximately 0.1775″. In the FIG. 59 embodiment, and in a firstembodiment, the distance 672 is approximately 2.1772 inches orapproximately 2 inches greater.

It should also be noted that the center line 670 of the driveshaft hasnot been lowered relative to a ground plane 676 but rather the remainingportion of the chassis has been raised relative to the ground plane 676.In the embodiment shown, the body panel 650 has been raised byapproximately two inches relative to the ground plane 676. As shown, andin a first embodiment, the distance 677 between the body panel 650 andthe ground plane 676 is 9.12 inches (231.647 mm). In the embodimentdepicted in FIG. 53, the corresponding distance 678 is 7.261 inches(184.432 mm). Thus, the end result of the design changes mentioned abovehas raised the ground clearance of the body panel 650 relative to theground plane, and relative to the top surface of the snow.

Specifically, this has been accomplished by providing a revised bulkheadportion 608A (FIGS. 56 and 60), which is provided with a semi-circularportion 608B profiled to receive the drive mechanism 640. Bulkheadportion 608A defines a drive shaft mount portion for drive mechanism640. In addition, and as mentioned above, the revised spindle 634 hasbeen elongated which raises the location of the upper and lower controlarms relative to the previous snowmobiles.

Also, the tunnel 606 is raised relative to the ground by moving theconnection of the front control arm 616 relative to the tunnel 606.Namely, the connection point between the two is shown at 690 in FIG. 55.As shown in FIG. 59, the distance from the bottom of the chassis at 650to the connection point 690 is shown as distance 686. In the firstembodiment, the distance 686 is 3.34 inches (84.84 mm) and in theembodiment of FIG. 53, the analogous distance 674 is 5.34 inches (135.64mm).

In a second embodiment, the corresponding distances have been slightlyaltered. Namely, in a second embodiment, the relevant distances are:

672=1.5 inches (38.10 mm)

677=8.34 inches (211.84 mm)

680=6.2 inches (157.48 mm)

686=3.97 inches (100.84 mm)

Thus as shown below, two embodiments have been described with thefollowing dimensions:

Dimension Dimension Dimension Dimension 672 677 680 686 Embodiment 12.13 inches 9.30 inches 6.9 inches 3.34 inches (54.10 mm) (36.22 mm)(175.26 mm) (84.84 mm) Embodiment 2 1.5 inches 8.34 inches 6.2 inches3.97 inches (38.10 mm) (211.84 mm) (157.48 mm) (100.84 mm) General Range1.25-2.25 inches 8-10 inches 6-7 inches 3-4.25 inches (31.75-57.15 mm)(203-254 mm) (152.4-177.8 mm) (76.2-107.95 mm)

All measurements mentioned herein are taken at static condition in fullrebound.

Multiple other possibilities and embodiments now present themselves withthe modified relative location of driveshaft 640. These changes includelowering the height of the tunnel and the jackshaft, repositioning thelocation of the fuel tank, among others as described below.

With reference now to FIG. 60, snowmobile 602 is shown in sectionthrough drive shaft 640. It should be appreciated that the drivemechanism 640 is shown modified in the chassis of FIG. 1, with thechanges being the raised chassis and elongated spindles 634. Thus, asinstalled in the tunnel of the FIG. 1 embodiment, the space between thesprockets 652/track has been increased relative to the bottom of thetunnel 606, since the chassis has been raised relative to the drivemechanism 640 as discussed above. Therefore, the tunnel itself could belowered relative to that shown in FIG. 55.

With reference again to FIG. 55, tunnel 606 could be lowered byapproximately two inches such that the top of the tunnel isapproximately at the dashed line 700. Since the tunnel may be lowered,other components which are restricted by the height of the tunnel 606may also be lowered. For example, the fuel tank (not shown) than runslongitudinally along the tunnel, may be more centralized towards thecenter of the vehicle, given the extra volume now available by the addedtwo inches.

Also with respect again to FIG. 8, a chain case 710 is shown having asprocket 712, which would drive the drive shaft 640 through sprocket 714and chain 716. A jackshaft (not shown) would extend between sprocket 712and though sidewall 718, where a bearing (not shown) would reside inopening 720, and thereafter connect to the CVT pulley. The jackshaftwould be driven by the engine/CVT. Thus, as the chassis has been raisedrelative to the driveshaft, the jackshaft can be positioned above thetunnel, but lower and out of the intake track of the engine. This allowsfor horse power enhancement of the engine and potentially allows morespace for a larger air box for performance gains of the engine.

In addition, the tunnel typically has an integrated cooling system asdescribed above. As the tunnel is lowered, so too is the cooling liquidwithin the tunnel and therefore the center of gravity (CG) of the tunnelis lowered. Also, by lowering the jackshaft, the clutch and brake(attached to jackshaft) are also lowered. Thus, even though the CG ofthe front chassis has been raised by raising the front chassis portion608 as described above, at least some of the vehicle height increase hasbeen offset by lowering the CG of the tunnel and other chassis parts.

While this invention has been described as having an exemplary design,the present invention may be further modified within the spirit andscope of this disclosure. This application is therefore intended tocover any variations, uses, or adaptations of the invention using itsgeneral principles. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this invention pertains.

What is claimed is:
 1. A snowmobile, comprising: a chassis comprising afront portion and a tunnel, the front portion having a front lower edgeand a drive shaft mount portion; a propulsion unit comprising a driveshaft, the drive shaft being rotatably coupled to the chassis driveshaft mount portion with a centerline of the drive shaft being proximateto the front lower edge of the chassis; a front suspension, comprisingright and left upper control arms, right and left lower control arms, aright spindle coupled to the right upper control arm and right lowercontrol arm, and a left spindle coupled to the left upper control armand left lower control arm; and skis coupled to a lower end of the rightand left spindles; wherein a ratio of a first value to a second value isbetween approximately 2.66 to approximately 4.80, the first value beinga linear distance between a connection point of the right and left lowercontrol arms of the front suspension to the respective right and leftspindles and the second value being a linear distance between the frontlower edge of the chassis and the lower outer diameter of the driveshaft.
 2. The snowmobile of claim 1, wherein the drive shaft mountportion extends lower than the front lower edge.
 3. The snowmobile ofclaim 2, wherein a vertical distance between front lower edge of thechassis and the lower outer diameter of the drive shaft is approximately1.5″.
 4. The snowmobile of claim 2, wherein a vertical distance betweenthe front lower edge of the chassis and the lower outer diameter of thedrive shaft is in the range of approximately 1.25-2.25″.
 5. Thesnowmobile of claim 1, wherein the chassis includes left and right frontframe portions and a body portion extending beneath the left and rightfront frame portions forming an underside surface of the snowmobile. 6.The snowmobile of claim 5, wherein the skis have an underside surfaceand a distance between the underside surface of the body portion and theunderside surface of the skis is at least approximately 8.3 inches. 7.The snowmobile of claim 1, wherein the distance between a connectionpoint of the right and left lower control arms to respective a right andleft spindles and a connection point for the skis coupled to the lowerends of the right and left spindles is approximately less than 7″.